Why do toddlers need to nap? Toddlers need to nap to support their growth and development. Their bodies and brains are growing at very rapid rates and they need time to recharge and process all of the many things they are learning all. of. the. time. In addition, toddlers are little people, just like us, who become irritable without enough sleep. Your toddler will be much happier and better behaved with adequate sleep, which will also cut down on temper tantrums (but we can't guarantee